This invention relates to a suction control device for an endoscope adapted to suction, air and water feeding, insertion of forceps or other treatment appliances, etc., by means of a channel.
In general, a suction control device of an endoscope is used for removing mucus, waste, etc., from the body cavity by suction. Such a suction control device, however, is so designed as to be able to be also used for insertion of a treatment appliance and injection of a medical fluid into the body cavity.
Conventionally, the suction control device of this type is constructed as shown in FIG. 1. In FIG. 1, numeral 1 designates an outer cylinder which has its peripheral wall connected with a suction tube 2 and its lower end with a channel of the endoscope. Disposed in the outer cylinder 1 is a guide cylinder 5 which consists of a first cylinder portion 3 and a second cylinder portion 4 with its lower end screwed in the upper end of the first cylinder portion 3, defining a space portion 6 between these two cylinders. A slide cylinder 7 is fitted in the guide cylinder 5, and is elastically held by means of a compression spring 8 interposed between the outer peripheral surface of the slide cylinder 7 and the inner peripheral surface of the guide cylinder 5. A support cylinder 10 is coupled with the lower end of the slide cylinder 7 by means of a coupling cylinder 9. Held in the support cylinder 10 is a slider 12 having a central communication hole 11 through which a treatment appliance is passed. Further, a communication hole 13 connecting the space portion 6 with the interior of the guide cylinder 5 is bored through the peripheral wall of the first cylinder portion 3 below the slider 12. A cap 14 is fitted on the top of the outer cylinder 1. The cap 14 is provided with a holding hole 15 fitted airtightly with the upper end portion of the guide cylinder 5 and an air hole 16 for connecting the space portion 6 with the open air.
In sucking mucus or waste from a body cavity, both the holding hole 15 and the air hole 16 are blocked up with a finger. Then, a sucking force in the suction tube 2, having so far been sucking the open air through the air hole 16 and the space portion 6, acts on the interior of the body cavity through the channel, as indicated by arrow a in FIG. 1. As a result, the mucus or waste in the body cavity is sucked into the suction tube 2. In making both treatment with use of the treatment appliance and suction at the same time, the appliance is inserted into the channel through the slide cylinder 7 and the communication hole 11 of the slider 12, and the air hole 16 is blocked up with a finger. In liquid feeding, moreover, the distal end portion of an injector is fitted in the slide tube 7, and the slide tube 7 is pushed and slidden against the restoring force of the spring 8 to cause the communication hole 13 to be blocked up by the slider 12 which shifts its position together with the slide cylinder 7. Then, the interior of the guide cylinder 5 is cut off from the space portion 6 to allow a liquid to be fed from the injector into the body cavity through the channel.
In the prior art suction control device of the above-mentioned construction, however, the three cylinders, i.e., the outer cylinder 1, the guide cylinder 5, and the slide cylinder 7, are required for the versatility of the device, and moreover the spring 8 need be interposed between the guide cylinder 5 and the slide cylinder 7. Thus, the number of components required is increased, and the assembly work is complicated to result in an increase in cost as well as a reduction in productivity. Since the slider 12 to block up the communication hole 13 at liquid feeding is slidably fitted in the guide cylinder 5, it is impossible securely to seal the sliding surface of the slider 12. Accordingly, part of the liquid delivered from the injector may be sucked through the space portion 6 into the suction tube 2, prohibiting satisfactory feeding of the liquid into the body cavity. Moreover, the aforesaid complicated construction makes it impossible to wash out mucus or waste part of which would inevitably penetrate to the region of the spring 8 and its vicinities through the gap between the respective sliding surfaces of the guide cylinder 5 and the support cylinder 10 at the suction of such mucus or waste from the body cavity.